Older Road User Crashes

Monash University Accident Research Centre - Report #61 - 1994

Authors: B. Fildes, B. Corben, S. Kent, J. Oxley, T. Le & P. Ryan

Full report in .pdf format [482KB]

Abstract:

The aim of this study was to examine the accident involvement of elderly road users with a view to identifying incidence numbers and rates, target groups of accidents where older road users are over-represented, suitable countermeasures, and areas requiring further research. A review of the international literature was undertaken to highlight the extent of the older road user problem and directions and hypotheses for subsequent analyses. Analyses were conducted of recent casualty crashes in Victoria. Areas investigated included: driver and pedestrian accident trends over the last ten years, driver and pedestrian injuries and associated treatment and rehabilitation costs, and road and environment characteristics of driver and pedestrian casualty crashes. Results showed that the number and rates per head of population of casualty crashes amongst elderly road users have been generally decreasing since 1989 although this decline was more apparent for pedestrians than it was for drivers. Although they constitute only a relatively small proportion of crash casualties, older road users are far more likely to be severely injured in the event of a crash and more likely to sustain serious chest injuries than their younger counterparts. Older drivers represent about 5% of the total cost of trauma to drivers in the state of Victoria; older pedestrians, however, represent about 14% of the total cost of pedestrian trauma in this state. Older road users appear to be over-involved in crashes at intersections, particularly at cross intersections and those controlled by stop and give-way signs, and tend to have their crashes during daylight hours between 9a.m. and 3p.m. The results also suggested that older road users are over-involved in crash configurations with a relatively high level of complexity. The results are discussed in terms of their implications for interventions aimed at older drivers and pedestrians and for current issues such as older driver licence testing. Areas for further research identified in this study are also discussed.

Executive Summary

INTRODUCTION

As the proportion of elderly people in Australia is increasing, so too is concern for the safety of the elderly in all types of environments. The accident risk of older road users is one area which is attracting increasing attention, especially given that the ageing process is associated with increases in functional disabilities which may impair driving safety and mobility. Overseas evidence suggests that older drivers and pedestrians do not represent a sizeable proportion of the road crash statistics; however, their risk of crash involvement per head of population or kilometre travelled is quite high. Moreover, once involved in a crash, older people have a higher risk of severe injury or death due to their increased frailty.

There have also been recent calls for mandatory licence retesting for older drivers in the State of Victoria. The consequences of such a scheme, with its potential to severely limit the mobility of older people, require careful consideration.

These current trends highlighted a need for more detailed research examining the nature and extent of the older road user problem in the State of Victoria.

PROJECT OBJECTIVES AND TASKS

The aim of this study was to conduct an extensive analysis of Victorian road accident data in order to highlight recent trends among older drivers and pedestrians, the types and severity of injuries sustained, associated road trauma cost, and the types of crashes in which the elderly seem to be over-involved. The study was divided into three main tasks:

1. A review of the international literature was conducted to demonstrate the extent of the older road user problem and to highlight directions and hypotheses for subsequent testing. The review contained a comprehensive account of the sensory, motor and cognitive effects of ageing and their implications for driver and pedestrian safety. Additionally, various characteristics of the road environment associated with crashes among older road users were identified, and existing countermeasures and interventions designed to improve the safety of' the elderly in the road environment were reviewed.

2. Detailed analyses were carried out of two road crash databases containing information on casualty crashes in the State of Victoria over several years. Ten years of data from the VicRoads database of police-reported casualty crashes were analysed to demonstrate older road user accident trends. Two years of recent data from the Transport Accident Commission (TAC) database of no-fault injury compensation claims were analysed to examine injuries and associated treatment and rehabilitation costs.

Three recent years of police data were analysed in order to determine specific road and environmental characteristics causing problems for older road users.

3. The findings were then reviewed in terms of their implications for existing or future countermeasures to reduce the frequency and severity of road trauma to the elderly. Areas requiring further research were also identified.

FINDINGS FOR OLDER DRIVERS

Crash Trends

The numbers and rates of casualty crashes per head of population peaked in Victoria in 1989 and have been progressively decreasing since then. However, the decrease is more marked for younger than older drivers, possibly because older drivers have been less targeted and therefore less influenced by recent successful road safety initiatives such as speed cameras and Random Breath Testing. Economic recession factors may also have less effect on the amount of driving done by older drivers by comparison with their younger counterparts.

The average annual casualty rates per 100,000 population for drivers were highest for those aged 17 to 24 years and steadily declined until age 74, after which they started to rise slowly again. Casualty rates per million kilometres travelled, however, show that older drivers are especially at risk.

Injuries & Costs

Older drivers accounted for only 7% of all driver claims on the TAC during 199 1. Moreover, while older driver crashes were estimated to cost the Victorian community more than $23 million annually, they represent only 5% of the total yearly cost of driver trauma in the State.

The average claim cost on the TAC for an older driver was roughly one-third less than for younger drivers. Although older drivers had higher claim costs for hospitalisation and rehabilitation, they had relatively low claim costs for death benefits, loss of earnings and earning capacity, compared with younger drivers.

Older and younger drivers sustained very similar injuries in casualty crashes, except for a slightly higher likelihood for older drivers to sustain a major or minor chest injury. This probably reflects their greater frailty and hence increased susceptibility to rib and sternum fractures from the seatbelt in crashes.

Crash Characteristics

Analysis of the last three years of data from police-reported casualty crashes highlighted a number of road, driver and environmental aspects of older driver crashes. However, it should be stressed that while these findings might suggest areas of risk for older road users, they also indicate times and locations where older road users are more likely to have their crashes, that is, where they are over-exposed. Without adequate exposure data, it is not possible to differentiate between increased risk of a crash or over-exposure.

Older drivers were over-involved in crashes at intersections, particularly cross and unsignalised intersections (stop and give way controls). They were also over-involved in crash configurations involving a relatively high degree of complexity (e.g., cross traffic, right-through, and U-turn collisions).

There was a high preponderance of older driver crashes on dry roads (80%), during the day (87%), and between the hours of 9am and 3pm (54%). These findings probably reflect the fact that older drivers tend to driver more during off-peak times during the day and in urban areas where there is less demand on their perceptual and cognitive abilities.

Older drivers involved in casualty crashes also tended to be male (69%) and to have had a blood alcohol level well below the legal limit (90% had either zero or very low BACs).

FINDINGS FOR OLDER PEDESTRIANS

Crash Trends

The number and rate per 100,000 population also peaked for pedestrian crashes in 1988 and have been slowly falling since then for both young and old pedestrians alike.

Casualty rates for pedestrians injured on the road are high during early adulthood, progressively fall until age 44, and then subsequently rise again with increasing age (most markedly for serious injuries and fatalities). These findings probably confound both risk and exposure factors across the various age groups.

Injuries & Costs

Contrary to the findings for driver trauma, older people account for a much larger proportion of pedestrian accident claims on the TAC (27%) as well as a much larger share of all pedestrian trauma costs (14%). Older pedestrian crashes were estimated to cost the Victorian community more than $14 million annually. The average claim cost on the TAC for older pedestrians was again around one-third less than for younger pedestrians.

Pedestrians had more age-related differences in injuries sustained in casualty crashes in contrast to the driver findings reported above. Older pedestrians had more major head, chest and upper limb injuries, most likely reflecting their increased frailty and vulnerability to injury in casualty crashes. Of note, the likelihood of a serious or fatal injury, given a crash was 54% for older pedestrians, compared to only 19% for older drivers.

Crash Characteristics

There were a number of age-related characteristics of pedestrian crashes observed in these data, although again, some of these may simply reflect over-exposure rather than increased risk.

Older pedestrians were over-represented in crashes at cross and unsignalised intersections, compared to their younger counterparts. When crossing the road, older pedestrians were equally vulnerable in both near- and far-side collisions, suggesting that these crashes involve more than just reduced mobility among the elderly.

As for drivers, older pedestrians were over-represented among crashes occurring during the day (84%) and between the hours of 9am and 3pm (54%). Further, most of these crashes occurred during the week (83%) and in 6Okm/h zones (95%), again emphasising exposure patterns among older pedestrians.

Unlike drivers, however, the majority of older pedestrian casualty crashes were female which is also probably an over-exposure finding, given that 58% of the population aged 65 years and older are women.

OPPORTUNITIES FOR INTERVENTION

The results suggested a number of areas where intervention may be warranted to reduce the frequency and/or severity of injuries to older road users. In some instances, further work is still required to specify and develop suitable measures. Some of the suggested areas for intervention included:

  • improved protection for older car occupants, especially measures aimed at reducing the number of chest injuries (eg: airbags, better belt systems, airbelts, etc.);
  • greater consideration of the perceptual, physical and cognitive abilities of older road users in road design and traffic control, comprising measures such as:

(i) increased use of traffic signals and pedestrian crossings in areas where the proportion of older road users is known to be high;

(ii) improved intersection design to assist older people crossing the road (eg; longer walk cycles, clear road markings, lower kerb edges, more refuge areas);

(iii) greater use of roundabouts to enhance traffic control and increase safety for older road users at low volume intersections;

  • informing older road users of situations where they are most vulnerable and ways in which they can minimise their risk of injury; and
  • publicity to alert all road users to the special problems encountered by older people when using the road.

RECOMMENDATIONS FOR FURTHER RESEARCH

Given the lack of previous work in this area, the study was particularly interested in highlighting the needs for further research aimed at improving older road user safety. This included:

  • the need for greater understanding of the role of the ageing process and the associated physical, perceptual and cognitive deficits in crashes involving older people;
  • improved knowledge of older road user travel patterns for both drivers and pedestrians to separate risk from exposure features of their crashes;
  • detailed investigations to highlight functional characteristics of older driver crashes and establish meaningful criteria for determining which older drivers are at risk on -the roads; and
  • the trade-off in crash or injury risk (and the subsequent cost to the community) when an older person stops driving and becomes a pedestrian.

Sponsoring Organisation: Baseline Research Program - Department of Justice, Transport Accident Commission, Royal Automobile Club of Victoria (RACV) Ltd, VicRoads